The Tony Award-winning actor has been preparing to play the opera singer in the biopic - entitled 'One Chance' - for some time, but has now had the dental work necessary to look like the eccentric star.

A source said: ''James spent six hours in the dentist's chair at Ealing Studios with an army of people chipping in.

''The full make-up and wardrobe team had a say, with the director, producers and exec producers offering their thoughts.

''He filmed a full camera test ahead of filming kicking off next week.''

Producers on the film, which is being funded by Harvey Weinstein, are keen to get the star's bad teeth exactly right.

The source added to The Sun newspaper: ''It's such a key part of the project to get right. Paul Potts is a distinctive-looking bloke, and his face is so well known in the UK, they have to get it spot on.''

Paul rose to fame in 2007 when he won 'Britain's Got Talent' singing 'Nessun Dorma', having previously been a mobile phone salesman.